A recording method has heretofore been known, in which an optical disc comprising a plastic disc with a thermally deformable metal (e.g., tellurium and bismuth) coating provided thereon is scanned with a laser beam modulated by a tracking signal or information to record the tracking signal or information in the metal coating as a bit line. Such a method is described in, for example, G. C. Kenny et al, An Optical Disc Replaces 25 Mag Tapes, IEEE Spectrum, pp. 33-38, February (1979) and R. A. Bartolini et al, Optical Disk Systems Emerge, IEEE Spectrum, pp. 20-28, August (1978).
In order to copy the information recorded in an optical disc, useful methods include those in which a stamper is produced from the original disc by a technique, such as nickel plating, the surface of a plastic substrate is subjected to thermal processing using the stamper to form a plastic mold, and a metal coating is applied on the surface of the plastic mold by a method such as vapor deposition. Methods of this type are disadvantageous in that prolonged working time is required and the procedure becomes complicated.
Recently, there has been proposed a copying method in which a master mask with information recorded therein, e.g., a micro film, is exposed to flash irradiation to copy the recorded information (see, for example, U.S. Pat. Nos. 4,000,334, 4,267,261 and 4,199,615). In any of the methods disclosed in the above references, however, flash irradiation of 10 microseconds to several hundred milliseconds is applied. This causes the diffusion of heat in the recording layer in the crosswise direction during the period of recording. This results in the ability to obtain only a low resolving power.
The object of the invention, therefore, is to provide a method free of the above described defects and which makes it possible to copy optical information in a very short period of time and at a high resolving power of 1 .mu.m or less.